Stop the Spear Phishing: Stopping other people from using your domain name!
One of the methods used by scammers is to impersonate someone from your own domain name, e.g. you get an email from accounts@yourdomain.com.au telling you open email attachments or click links. One of the best ways to stop this is using DKIM, DMARC and SPF.
3CX Voicemail User Guide
The 3CX Voicemail is handy, and if you wait long enough the system will prompt you with option, but if you are impatient (like me!) then this guide might help!